Cadaveric anatomy of the lumbar triangular safe zone of Kambin’s in North West Indian population

A three dimensional triangular space ‘the Kambin’s triangle (KT)’ present on the dorsolateral aspect of the intervertebral disc, is considered to be a safe area for transforaminal approaches. It allows access to the exiting and traversing nerve roots, the thecal sac and to the intervertebral disc spaces. Our aim was to calculate the area of the triangle by measuring the height and base at all the intervertebral spaces bilaterally in the lumbar region in North West Indian cadavers and to assess the diameter of circle inscribed within this triangle which will correspond to the size of cannula inserted for the minimally invasive transforaminal approaches in this population. Five randomly chosen adult cadavers were used for this study. After clearing the area, the exiting nerve was identified. The height and base of the bony KTs (n=40) were measured with the help of digital Vernier’s calliper (accuracy 0.02 mm) to calculate the area of the KT. There is a steady increase in the area of the bony KT reaching maximum at the level of L4-5 intervertebral space. Statistically there were no differences in the calculated areas between right and left side. The mean diameter of inscribed circle within the triangle also showed gradual increase from 5.82 mm at L1-2 level, reaching maximum value of 7.26 mm at L4-5 level on the right side while on the left side the values were 5.66 mm and 8.16 mm respectively. Careful anatomical consideration is of utmost importance in transforaminal approaches during surgical or interventional procedures in this region. Cannula having external diameter ranging 6–8 mm is recommended for any interventional approach through Kambin’s space.